Presently, I have a SFH appx 1390 sqft. I discussed with few arch/builders to add additional 800 sqft for two bed and two baths.
After seeing the lot, one builder told me to extend either 1000 sqft or 1200 sqft instead of 800 sqft. He is telling me that some of the fixed cost like truck, bobcat and other rental equipment are fixed cost whether I add 800 sqft or 1200 sqft.
He hinted by increasing the sqft, the cost/sqft will come down and it will be economical for me to add more sqft than modifying internal home.
When I calculate $320/sqft for 800 sqft addition, he is hinting that I may get $280/sqft for 1200 sqft addition.
The lot allows me to go up to 2000 sqft easily. Is it reliable that cost/sqft comes down when I go for bigger extension?
So your total cost is 256K for 800 sqft vs 336K for 1200 sqft. I am also in the same exact boat right now for planning addition next year. My first thought is to go with 800sqft, but right now, we are leaning towards to max efficiency and spending extra 50-70K and go for more value.
Even if economic value doesn’t go down to $280/sqft, you can be conservative and fine to calculate with $300. Cost like architect and permit are more fixed costs too. You can estimate your future value of 2200 sqft house vs 2600 sqft house.
That’s where we feel like clear winner for us - value of 1900 sqft vs 2200 sqft house in our situation for 4/3.
As a building contractor here in Fremont , I do agree that the per Sq.ft price will drop as the square footage increases. I’ve personally seen this on my past projects. For example, a 500 sqft addition will not be the same per ft price as a 2000 sq ft home.